Mach reflection bifurcations as a mechanism of cell multiplication in gaseous detonations

• Published in: Proceedings of the Combustion Institute Vol. 33; no. 2; pp. 2279 - 2285
• Main Authors: Mach, P., Radulescu, M.I.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 2011
• Subjects: Asymmetry; Bifurcation; Bifurcations; Cellular structure; Detonation; Detonation waves; Instability; Mathematical analysis; Mathematical models; Multiplication; Shock reflection; Bifurcation; Instability; Detonation; Shock reflection; Cellular structure
• ISSN: 1540-7489; 1873-2704
• DOI: 10.1016/j.proci.2010.06.145

Detonation waves in gases are unstable and form cellular structures. The cellular structure can range from being very regular, to very irregular, where new modes are continuously formed on the front of the detonation wave. The present work addresses the mechanism of new cell formation in irregular structure detonations. Using idealized one-step chemistry calculations on sufficiently wide domains, as to avoid mode-locking, the present work reveals a novel mechanism for new mode formation in cellular detonations. The mechanism involves the creation of wave bifurcations on the front of the Mach shock following triple shock collisions. The numerical simulations reveal that these new triple points, through further reflections with pre-existing modes in asymmetric cells, can give rise to cell multiplication. Parameters favourable to this mechanism were found in good correlation with parameters leading to irregular cellular structures, as observed in previous experiments.